Ion implanter

ABSTRACT

An ion implanter includes: a main body which includes a plurality of units which are disposed along a beamline along which an ion beam is transported, and a substrate transferring/processing unit which is disposed farthest downstream of the beamline, and has a neutron ray source in which a neutron ray is generated due to collision of a ultrahigh energy ion beam; an enclosure which at least partially encloses the main body; and a neutron ray scattering member which is disposed at a position where a neutron ray which is emitted from the neutron ray source is incident in a direction in which a distance from the neutron ray source to the enclosure is equal to or less than a predetermined value.

RELATED APPLICATIONS

The content of Japanese Patent Application No. 2019-051014, on the basisof which priority benefits are claimed in an accompanying applicationdata sheet, is in its entirety incorporated herein by reference.

BACKGROUND Technical Field

Certain embodiments of the present invention relate to an ion implanter.

Description of Related Art

In a semiconductor manufacturing process, for the purpose of changingconductivity, the purpose of changing the crystal structure of asemiconductor wafer, or the like, a process of implanting ions into thesemiconductor wafer is carried out standardly. An apparatus which isused in this process is generally called an ion implanter. The ionimplantation energy is determined according to a desired implantationdepth of ions which are implanted near the surface of the wafer. An ionbeam having low energy is used for implantation into a shallow region,and an ion beam having ultrahigh energy is used for implantation into adeep region.

Recently, for implantation into a deeper region, there is an increasingdemand for so-called ultrahigh energy ion implantation which uses an ionbeam having higher energy than in ultrahigh energy ion implantation ofthe related art. There is a possibility of a nuclear reaction induced ina case where ions accelerated to ultrahigh energy collides with memberswhich are present in a beamline of an ion implanter. Depending on thenuclear reaction that occurs, radiation such as neutron rays can begenerated.

SUMMARY

According to an embodiment of the present invention, there is providedan ion implanter including: a main body which includes a plurality ofunits which are disposed along a beamline along which an ion beam istransported, and a substrate transferring/processing unit which isdisposed farthest downstream of the beamline, and has a neutron raysource in which a neutron ray is generated due to collision of aultrahigh energy ion beam; an enclosure which at least partiallyencloses the main body; and a neutron ray scattering member which isdisposed at a position where the neutron ray which is emitted from theneutron ray source is incident in a direction in which a distance fromthe neutron ray source to the enclosure is equal to or less than apredetermined value.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram schematically showing a neutron ray scatteringmember which is provided in an enclosure.

FIG. 2 is a cross-sectional view schematically showing a structure of anaccommodation part.

FIG. 3 is a diagram schematically showing a neutron ray scatteringmember which is provided separately from the enclosure.

FIG. 4 is a top view showing a schematic configuration of an ionimplanter according to an embodiment.

FIGS. 5A to 5C are side views showing a schematic configuration of theion implanter of FIG. 4.

FIG. 6 is a top view schematically showing a structure of a front doorof a load port.

FIGS. 7A and 7B are top views schematically showing the front door inthe open states of the load port.

FIG. 8 is a flowchart showing a flow of an ion implantation processaccording to the embodiment.

FIG. 9 is a diagram schematically showing the ion implanter in a firstprocess.

FIG. 10 is a diagram schematically showing the ion implanter in a secondprocess.

FIG. 11 is a diagram schematically showing the ion implanter in a thirdprocess.

FIG. 12 is a diagram schematically showing the ion implanter in a fourthprocess.

FIG. 13 is a diagram schematically showing the ion implanter in a fifthprocess.

FIG. 14 is a diagram schematically showing the ion implanter in a sixthprocess.

DETAILED DESCRIPTION

In the case of an ultrahigh energy ion implanter in which generation ofa neutron ray is a concern, it is also conceivable to install the entireimplanter in a radiation controlled area. However, it is not easy toseparately provide a radiation controlled area in a semiconductormanufacturing factory for mass production.

It is desirable to provide an ion implanter in which it is possible tosuppress the neutron dose rate outside of the apparatus.

Any combination of the constituent elements described above, orreplacement of constituent elements or expressions of the presentinvention with each other between methods, apparatuses, systems, or thelike is also valid as an aspect of the present invention.

According to the present invention, an ion implanter in which a neutrondose rate outside of the implanter is suppressed can be provided.

Hereinafter, modes for carrying out the present invention will bedescribed in detail with reference to the drawings. In the descriptionof the drawings, the same elements are denoted by the same referencenumerals, and overlapping description is omitted appropriately. Further,the configuration described below is an exemplification and does notlimit the scope of the present invention.

This embodiment relates to an ion implanter for ultrahigh energy ionimplantation. The ion implanter accelerates an ion beam extracted fromin an ion source, transports a ultrahigh energy ion beam obtained by theacceleration to a workpiece (for example, a substrate or a wafer W)along a beamline, and implants ions into the workpiece.

The term “ultrahigh energy” in this embodiment refers to the energy ofan ion beam having an energy of 4 MeV or higher, 5 MeV or higher, or 10MeV or higher. According to implantation of the ultrahigh energy ion,since desired impurity ions are implanted into a wafer surface withhigher energy than in ion implantation of an energy less than 4 MeV inthe related art, it is possible to implant the desired impurities into adeeper region (for example, a depth of 5 μm or more) of the wafersurface. The use of the ultrahigh energy ion implantation is essential,for example, to forming a P-type region and/or an N-type region in themanufacture of a semiconductor device such as the newest image sensor.

In the ion implanter for ultrahigh energy ion implantation, a ultrahighenergy ion beam collides with constituent members of a beamline, wherebyneutron rays can be generated. According to the knowledge of theinventors of the present invention, it is known that a neutron ray isgenerated in a case of using a boron ion beam having an energy of 4 MeVor higher. Specifically, with respect to boron ¹¹B that is anon-radioactive nuclide, nuclear reactions which are represented by thefollowing (1) and (2) can occur.¹¹B+¹¹B→²¹Ne+n  (1)¹¹B+¹²C→²²Ne+n  (2)

The above (1) is a nuclear reaction (also called a B-B reaction) inwhich boron ¹¹B and boron ¹¹B collide with each other to generate aneutron n. First, when an ion beam of boron ¹¹B is incident on (collideswith) the constituent member of the beamline, boron ¹¹B is accumulatedin a surface region of the constituent member. Thereafter, if the ionbeam of boron ¹¹B having ultrahigh energy collides with boron ¹¹Baccumulated in the surface region of the constituent member, the B-Breaction shown in the above (1) occurs to generate a neutron ray.

The above (2) is a nuclear reaction (also called a B-C reaction) inwhich boron ¹¹B and carbon ¹²C collide with each other to generate aneutron n. Since at least apart of the constituent member of thebeamline is made of graphite (that is, carbon), the ion beam of boron¹¹B having ultrahigh energy collides with the graphite, whereby the B-Creaction shown in the above (2) occurs to generate a neutron ray. Boron¹¹B is accumulated in the surface region of graphite, whereby a neutronray due to the B-B reaction of the above (1) can also be generated.

In this manner, in the ion implanter for ultrahigh energy ionimplantation, although a radioactive nuclide is not included in theimplanted ion, the ultrahigh energy ion beam collides with variouslocations of the beamline, whereby radioactive nuclides are generated,so that neutron rays can be generated. Therefore, the ion implanter forultrahigh energy ion implantation has a neutron ray source capable ofgenerating a neutron ray due to collision of a ultrahigh energy ionbeam. Therefore, in the ion implanter for ultrahigh energy ionimplantation, it is necessary to appropriately manage the neutron raywhich is generated at the neutron ray source.

In general, in a case of dealing with an apparatus in which radiationsuch as a neutron ray is generated, an operation method is considered inwhich a dedicated radiation controlled area is provided and theapparatus is installed in the area. However, it is not easy toseparately provide the radiation controlled area in a semiconductormanufacturing factory for mass production. In the semiconductormanufacturing factory, it is necessary to transfer a wafer cassette orthe like at any time between the ion implanter and other apparatus, andin a case where the ion implanter is installed in the radiationcontrolled area, the wafer cassette or the like is transferred betweenthe controlled area and the non-controlled area. In order toappropriately shield the neutron ray, for example, a concrete wallhaving a thickness of several tens of centimeters or more is required,and a shielding door for loading and unloading the wafer cassette alsobecomes very thick. In this case, it is necessary to open and close thethick shielding door each time the wafer cassette is loaded andunloaded, which is a great labor. Further, if the operation of the ionimplanter has to be stopped when the shielding door is open, theproduction efficiency of semiconductor devices is reduced. Therefore,the inventors of the present invention have considered to allow aneutron dose rate outside of the enclosure to fall below the referencevalue stipulated by laws and regulations or the like by mounting aneutron ray scattering member to the enclosure surrounding the outerperiphery of a main body configuring a beamline.

As the radiation which is generated in the ion implanter for ultrahighenergy ion implantation, in addition to the neutron ray described above,X-rays is also involved. As an X-ray shielding member, a lead plate orthe like is mounted to the enclosure. X-rays are easily shieldedcompared to the neutron ray, and X-rays going out of the enclosure canbe sufficiently shielded by using a lead plate having a thickness in arange from about 1 mm to 5 mm, for example. On the other hand, it is noteasy to reduce the neutron dose rate. For example, in a case wheregeneral high-density polyethylene (specific gravity: about 0.95 g/cm³)is used as the neutron ray scattering member, a thickness in a rangefrom about 150 mm to 200 mm is required in order to attenuate theneutron dose rate to 1/10.

In order to reduce the neutron dose rate, it may be desirable to enclosethe entire implanter with a thick neutron ray scattering member.However, in the ion implanter for ultrahigh energy ion implantation,since an acceleration unit for accelerating the ion beam to ultrahighenergy becomes large, the area occupied by the main body becomes thearea of 10 m×20 m or more, for example, and the height of the main bodyalso exceeds 2 m. For this reason, if a neutron ray scattering memberhaving a large thickness is mounted over the entire implanter, a largeamount of neutron ray scattering members are required, leading to asignificant increase in cost and product weight, and thus, it is notpreferable.

In this embodiment, rather than aiming to completely shield the neutronray, the neutron ray scattering member is disposed mainly at a locationwhere there is a concern that the neutron dose rate may exceed apredetermined reference value stipulated by laws and regulations or thelike outside of the enclosure. Specifically, the disposition of theneutron ray scattering member is arranged according to the distance fromthe neutron ray source to the enclosure. This is because the neutrondose rate is inversely proportional to the square of the distance fromthe neutron ray source. The neutron dose rate increases at a locationwhere the distance from the neutron ray source to the enclosure is smalland decreases at a place where the distance from the neutron ray sourceto the enclosure is large.

The neutron dose rate which is generated in the neutron ray source inthis embodiment is not so large, and for example, the neutron dose rateat the distance of about 1 m from the neutron ray source is in a rangefrom about 0.1 to 2 μSv/h. Therefore, by disposing the neutron rayscattering member mainly at a location where the neutron dose rate isrelatively high, it becomes possible to suppress the neutron dose rateoutside of the enclosure to a value equal to or less than the referencevalue stipulated by laws and regulations or the like.

The “neutron ray scattering member” in this embodiment refers to amaterial having a large scattering effect with respect to a neutron ray.Hydrogen (H) or boron (B) is known as an element having a large neutronray scattering effect, and a material having a high content of hydrogenand/or boron is preferable as the neutron ray scattering member. Forexample, as a material having high hydrogen density, polyolefin such aspolyethylene or paraffin can be given, and a material having a hydrogenatom content in a range from 0.08 to 0.15 g/cm³ is preferable. As aspecific example, high-density polyethylene having a specific gravity ina range about from 0.94 to 0.97 g/cm³ can be given. Further, as theneutron ray scattering member, a high-density polyethylene in which aboron compound such as a boron oxide (B₂O₃) is contained in a rangeabout from 10% to 40% by weight may be used.

FIG. 1 is a diagram schematically showing neutron ray scattering members76 a and 76 b which are provided in an enclosure 70. The enclosure 70 isdisposed so as to surround the circumference of a device 78 configuringa beamline, and separates an external space E and an internal space Ffrom each other. A neutron ray source 79 is present in the interior ofthe device 78. The enclosure 70 has an outer surface 70 a which isexposed to the external space E and an inner surface 70 b which isexposed to the internal space F. The neutron ray scattering members 76 aand 76 b are provided inside of the enclosure 70, that is, between theouter surface 70 a and the inner surface 70 b of the enclosure 70.

The enclosure 70 has an accommodation part 71 (also simply referred toas an accommodation part) in which the neutron ray scattering members 76a and 76 b are provided, and a non-accommodation part 72 in which aneutron ray scattering member is not provided. The accommodation part 71includes a first accommodation part 71 a in which a first neutron rayscattering member 76 a having a relatively large thickness to isprovided, and a second accommodation part 71 b in which a second neutronray scattering member 76 b having a relatively small thickness tb isprovided.

The first neutron ray scattering member 76 a is disposed in a firstdirection (arrow Da) in which the distance from the neutron ray source79 to the outer surface 70 a of the enclosure 70 is a first distance,and is disposed at a position where a neutron ray which is emitted inthe first direction from the neutron ray source 79 can be incident. Thesecond neutron ray scattering member 76 b is disposed in a seconddirection (arrow Db) in which the distance from the neutron ray source79 to the outer surface 70 a of the enclosure 70 is a second distancelarger than the first distance, and is disposed at a position where aneutron ray which is emitted in the second direction from the neutronray source 79 can be incident. The thickness to of the first neutron rayscattering member 76 a is, 100 mm or more, for example, in a range aboutfrom 200 mm to 500 mm. On the other hand, the thickness tb of the secondneutron ray scattering member 76 b is, 50 mm or more, for example, in arange about from 100 mm to 200 mm. The first distance (Da) is, forexample, less than 2 m, less than 1.5 m, or less than 1 m, and thesecond distance (Db) is, for example, less than 10 m or less than 5 m,and is, for example, 2 m or more, 1.5 m or more, or 1 m or more.

A neutron ray scattering member is not disposed in a third direction(arrow Dc) in which the distance from the neutron ray source 79 to theouter surface 70 a of the enclosure 70 is a third distance larger thanthe first distance and the second distance. The third distance (Dc) is,for example, 5 m or more, 10 m or more, or 15 m or more. Therefore, inthis embodiment, the neutron ray scattering member is disposed in adirection in which the distance from the neutron ray source 79 to theouter surface 70 a of the enclosure 70 is equal to or less than apredetermined value (for example, the second distance), and the neutronray scattering member is not disposed in a direction in which thedistance from the neutron ray source 79 to the outer surface 70 a of theenclosure 70 exceeds another predetermined value (for example, the thirddistance).

It can be said that the first neutron ray scattering member 76 a isdisposed at a location where an angle difference θa between thethickness direction of the scattering member and the first direction(arrow Da) from the neutron ray source 79 toward the outer surface 70 aof the enclosure 70 is small. On the other hand, it can be said that thesecond neutron ray scattering member 76 b is disposed at a locationwhere an angle difference θb between the thickness direction of thescattering member and the second direction (arrow Db) from the neutronray source 79 toward the outer surface 70 a of the enclosure 70 islarge. Since the neutron ray which is directed from the neutron raysource 79 toward the first neutron ray scattering member 76 a can beincident on the first neutron ray scattering member 76 a at anapproximately right angle, the effective thickness (ta/cos(θa)) throughwhich the neutron ray passes and the actual thickness to of thescattering member are approximately equal to each other. On the otherhand, since the neutron ray which is directed from the neutron raysource 79 toward the second neutron ray scattering member 76 b can beobliquely incident on the second neutron ray scattering member 76 b, theeffective thickness (tb/cos(θb)) through which the neutron ray passes islarger than the actual thickness tb of the scattering member. For thisreason, even if the second neutron ray scattering member 76 b having therelatively small thickness tb is used, the neutron dose rate in theexternal space E outside of the enclosure 70 can be effectively reduced.

In the example of FIG. 1, the first accommodation part 71 a and thesecond accommodation part 71 b are disposed adjacently to each other,and the first accommodation part 71 a and the second accommodation part71 b are disposed so as to at least partially overlap each other in thethickness direction or the direction from the neutron ray source 79toward the outer surface 70 a. Further, the first neutron ray scatteringmember 76 a which is provided in the first accommodation part 71 a andthe second neutron ray scattering member 76 b which is provided in thesecond accommodation part 71 b are disposed so as to at least partiallyoverlap each other in the thickness direction or the direction from theneutron ray source 79 toward the outer surface 70 a. In this way, it ispossible to prevent a neutron ray having a high dose rate from leakingto the external space E through the gap between the first accommodationpart 71 a and the second accommodation part 71 b.

In the example of FIG. 1, the thicknesses of the neutron ray scatteringmembers 76 a and 76 b are changed in two stages. However, the thicknessof the neutron ray scattering member may be changed in three or morestages, or the thickness of the neutron ray scattering member may becontinuously changed. Further, in the first accommodation part 71 a andthe second accommodation part 71 b, plate-shaped or block-shaped neutronray scattering members having desired thicknesses ta and tb may be used,or a plurality of plate-shaped or block-shaped neutron ray scatteringmembers thinner than the desired thicknesses ta and tb may be used tooverlap each other in the thickness direction.

FIG. 2 is a diagram showing the structure of the accommodation part 71in detail. The accommodation part 71 has a main body frame 73 and a lidplate 74. An X-ray shielding member 75 and a neutron ray scatteringmember 76 are provided in the interior of the accommodation part 71. Themain body frame 73 is a support structure for supporting the X-rayshielding member 75 and the neutron ray scattering member 76, andconfigures the outer surface 70 a and a side surface 70 c of theaccommodation part 71. The lid plate 74 is mounted to the opening of themain body frame 73 and configures the inner surface 70 b of theaccommodation part 71. The main body frame 73 and the lid plate 74 aremade of a metal material such as iron or aluminum. The X-ray shieldingmember 75 and the neutron ray scattering member 76 are disposed tooverlap each other in the thickness direction, and are disposed, forexample, such that the X-ray shielding member 75 is on the outer surface70 a side and the neutron ray scattering member 76 is on the innersurface 70 b side. The X-ray shielding member 75 is, for example, a leadplate, and the neutron ray scattering member 76 is, for example, aplate-shaped or block-shaped high-density polyethylene. Instead ofproviding the lid plate 74, an incombustible sheet may be attached tothe surface on the inner surface 70 b side of the neutron ray scatteringmember 76. Further, an incombustible sheet may be additionally mountedbetween the lid plate 74 and the neutron ray scattering member 76. Theincombustible sheet is a sheet-like member which does not burn for acertain period of time (for example, 20 minutes) in a case of beingheated, and for example, a polyvinyl chloride (PVC) resin sheet, a resinsheet having glass fibers as a base material, a metal sheet, or the likecan be given.

The non-accommodation part 72 can be configured in the same manner asthe accommodation part 71 except that the neutron ray scattering member76 is not provided in the interior thereof. The non-accommodation part72 has, for example, the main body frame 73 and the lid plate 74 shownin FIG. 2, and the X-ray shielding member 75 is provided in the interiorof the non-accommodation part 72. The thickness of the non-accommodationpart 72 may be the same as the thickness of the accommodation part 71 ormay be smaller than the thickness of the accommodation part 71. Theinterior of the non-accommodation part 72 may be a cavity.

FIG. 3 is a diagram schematically showing neutron ray scattering members77 a and 77 b which are provided separately from the enclosure 70, andthe neutron ray scattering members 77 a and 77 b are mounted to thedevice 78 in which the neutron ray source 79 is present, or to thesupport structure of the device 78. Since the enclosure 70 is notprovided with a neutron ray scattering member, the enclosure 70 isconfigured as the non-accommodation part 72 described above. Anincombustible sheet may be attached to the surface of each of theneutron ray scattering members 77 a and 77 b.

Also in FIG. 3, the neutron ray scattering members 77 a and 77 b aredisposed according to the distance from the neutron ray source 79 to theouter surface 70 a of the enclosure 70. The first neutron ray scatteringmember 77 a having a large thickness to is disposed in the firstdirection (arrow Da) in which the distance from the neutron ray source79 to the outer surface 70 a of the enclosure 70 is the first distance,and is disposed at a position where the neutron ray which is emitted inthe first direction from the neutron ray source 79 can be incident. Thesecond neutron ray scattering member 77 b having a small thickness tb isdisposed in the second direction (arrow Db) in which the distance fromthe neutron ray source 79 to the outer surface 70 a of the enclosure 70is the second distance larger than the first distance, and is disposedat a position where the neutron ray which is emitted in the seconddirection from the neutron ray source 79 can be incident. On the otherhand, a neutron ray scattering member is not disposed in the thirddirection (arrow Dc) in which the distance from the neutron ray source79 to the outer surface 70 a of the enclosure 70 is the third distancelarger than the first distance and the second distance. The neutron rayscattering members 77 a and 77 b are disposed in this manner, whereby areduction effect of the neutron dose rate which is similar to that inthe configuration of FIG. 1 is expected.

In FIG. 3, since the neutron ray scattering members 77 a and 77 b aredisposed closer to the neutron ray source 79, the amount of neutron rayscattering members 77 a and 77 b which are required is smaller than thatof the neutron ray scattering members 76 a and 76 b in FIG. 1.Therefore, the disposition of the neutron ray scattering member in FIG.3 may be preferable to that in FIG. 1. However, there are variousdevices, cables, or the like around the device 78 configuring thebeamline, and thus it is not always easy to dispose the neutron rayscattering members in the vicinity of the device 78 without any gaps.Therefore, in this embodiment, the neutron ray scattering members 77 aand 77 b are appropriately disposed also in the vicinity of the mainbody, as shown in FIG. 3, while being based on the dispositions of theneutron ray scattering members 76 a and 76 b which are mounted to theenclosure 70, as shown in FIG. 1. In this way, the neutron dose rate inthe external space E of the enclosure 70 is equal to or less than thereference value while reducing the total amount of neutron rayscattering members in the entire implanter.

FIG. 4 is a top view schematically showing an ion implanter 100according to an embodiment. FIGS. 5A to 5C are side views showing aschematic configuration of the ion implanter in FIG. 4. FIG. 5Acorresponds to a cross section taken along the line A-A in FIG. 4, FIG.5B corresponds to a cross section taken along the line B-B in FIG. 4,and FIG. 5C corresponds to a cross section taken along the line C-C inFIG. 4.

The ion implanter 100 includes a main body 58 and an enclosure 60. Themain body 58 includes a beam generation unit 12, a beam accelerationunit 14, a beam deflection unit 16, a beam transport unit 18, and asubstrate transferring/processing unit 20. The enclosure 60 is disposedon the outer periphery of the main body 58 and at least partiallyencloses the main body 58. Although details will be described later, theneutron ray scattering members are disposed at hatched portions in thedrawing.

The beam generation unit 12 includes an ion source 10 and a massanalyzer 11. In the beam generation unit 12, an ion beam is extractedfrom the ion source 10, and the extracted ion beam is subjected to massanalysis by the mass analyzer 11. The mass analyzer 11 includes a massanalyzing magnet 11 a and a mass analyzing slit 11 b. The mass analyzingslit 11 b is disposed on the downstream side of the mass analyzingmagnet 11 a. As a result of the mass analysis by the mass analyzer 11,only ion species necessary for implantation are selected, and the ionbeam of the selected ion species is led to the following beamacceleration unit 14.

The beam acceleration unit 14 includes a plurality of linearacceleration units 22 a, 22 b, and 22 c that accelerate the ion beam,and a beam profile slit 23, and configures a linearly extending portionof a beamline BL. Each of the plurality of linear acceleration units 22a to 22 c includes one or more radio-frequency resonators andaccelerates the ion beam by causing a radio-frequency (RF) electricfield to act on the ion beam. The beam profile slit 23 is provided onthe farthest downstream side of the beam acceleration unit 14 and isused to measure the beam profile of the ultrahigh energy ion beamaccelerated by the plurality of linear acceleration units 22 a to 22 c.

In this embodiment, three linear acceleration units 22 a to 22 c areprovided. The first linear acceleration unit 22 a is provided at anupstream stage of the beam acceleration unit 14 and includes a pluralityof (for example, 5 to 10) radio-frequency resonators. The first linearacceleration unit 22 a performs “bunching” that fits a continuous beam(DC beam) which exits from the beam generation unit 12 to a specificacceleration phase, and accelerates the ion beam to an energy of about 1MeV, for example. The second linear acceleration unit 22 b is providedat a middle stage of the beam acceleration unit 14, and includes aplurality of (for example, 5 to 10) radio-frequency resonators. Thesecond linear acceleration unit 22 b accelerates the ion beam whichexits from the first linear acceleration unit 22 a to an energy in arange about from 2 to 3 MeV. The third linear acceleration unit 22 c isprovided at a downstream stage of the beam acceleration unit 14, andincludes a plurality of (for example, 5 to 10) radio-frequencyresonators. The third linear acceleration unit 22 c accelerates the ionbeam which exits from the second linear acceleration unit 22 b to aultrahigh energy of 4 MeV or higher.

In this embodiment, about 15 to 30 of radio-frequency resonators whichare included in the beam acceleration unit 14 are separately mounted onthe three linear acceleration units 22 a to 22 c. However, theconfiguration of the beam acceleration unit 14 is not limited to theillustrated configuration. The beam acceleration unit 14 may beconfigured as a single linear acceleration unit as a whole, or may beconfigured to be divided into two linear acceleration units or four ormore linear acceleration units. Further, the beam acceleration unit 14may be configured with any other type of acceleration unit, and mayinclude, for example, a tandem acceleration unit. This embodiment is notlimited to a specific ion acceleration method, and any beam accelerationunit can be adopted as long as it can generate an ultrahigh energy ionbeam of 4 MeV or higher.

The ultrahigh energy ion beam which exits from the beam accelerationunit 14 has a certain range of energy distribution. For this reason, inorder to irradiate a wafer with a ultrahigh energy ion beam that isreciprocally scanned and parallelized downstream of the beamacceleration unit 14, it is necessary to carry out high-accuracy energyanalysis, trajectory correction, and adjustment of beam convergence anddivergence in advance.

The beam deflection unit 16 performs energy analysis, energy dispersioncontrol, and trajectory correction of the ultrahigh energy ion beamwhich exits from the beam acceleration unit 14. The beam deflection unit16 configures a portion extending in an arc shape of the beamline BL.The ultrahigh energy ion beam is changed in direction by the beamdeflection unit 16 and directed to the beam transport unit 18.

The beam deflection unit 16 includes an energy analyzing electromagnet24, a laterally focusing quadrupole lens 26 which suppresses energydispersion, an energy analyzing slit 27, a first Faraday cup 28, and adeflection electromagnet 30 which provides beam steering (trajectorycorrection), and a second Faraday cup 31. The energy analyzingelectromagnet 24 is also called an energy filter electromagnet (EFM).Further, a device group which is composed of the energy analyzingelectromagnet 24, the laterally focusing quadrupole lens 26, the energyanalyzing slit 27, and the first Faraday cup 28 is collectively referredto as an “energy analyzer”.

The energy analyzing slit 27 is configured such that a slit width isvariable in order to adjust the resolution of energy analysis. Theenergy analyzing slit 27 is composed of, for example, two shieldingmembers movable in a slit width direction, and is configured such thatthe slit width can be adjusted by changing the interval between the twoshielding members. The energy analyzing slit 27 may be configured suchthat the slit width is variable by selecting any one of a plurality ofslits having different slit widths.

The first Faraday cup 28 is disposed immediately downstream of theenergy analyzing slit 27 and is used for beam current measurement forenergy analysis. The second Faraday cup 31 is disposed immediatelydownstream of the deflection electromagnet 30 and is provided for beamcurrent measurement of the ion beam which is subjected to the trajectorycorrection and enters the beam transport unit 18. Each of the firstFaraday cup 28 and the second Faraday cup 31 is configured to be able tobe inserted into and retracted from the beamline BL by the operation ofa Faraday cup driving unit (not shown).

The beam transport unit 18 configures a linearly extending portion ofthe beamline BL and is arranged to be parallel to the beam accelerationunit 14 with a maintenance area MA in the center of the implanterinterposed therebetween. The length of the beam transport unit 18 isdesigned to be approximately the same as the length of the beamacceleration unit 14. As a result, the beamline BL which is composed ofthe beam acceleration unit 14, the beam deflection unit 16, and the beamtransport unit 18 forms a U-shaped layout as a whole.

The beam transport unit 18 includes a beam shaper 32, a beam scanner 34,a beam dump 35, a beam parallelizer 36, a final energy filter 38, andleft and right Faraday cups 39L and 39R.

The beam shaper 32 includes a focusing and defocusing device such as aquadrupole focusing and defocusing lens (Q lens), and is configured toshape a profile of the ion beam that has passed through the beamdeflection unit 16 into a desired cross-sectional shape. The beam shaper32 is configured with, for example, an electric field type three-stagequadrupole lens (also referred to as a triplet Q lens), and has threequadrupole lenses. By using three lenses, the beam shaper 32 canindependently adjust the convergence or divergence of the ion beam ineach of the horizontal direction (x direction) and the verticaldirection (y direction). The beam shaper 32 may include a magnetic fieldtype lens, or may include a lens that shapes a beam profile by usingboth an electric field and a magnetic field.

The beam scanner 34 is a beam deflector which is configured to provide areciprocal scanning of a beam and performs scanning with the shaped ionbeam in the x direction. The beam scanner 34 has a scanning electrodepair facing each other in the beam scanning direction (x direction). Thescanning electrode pair is connected to a variable voltage power source(not shown), and by periodically changing a voltage which is appliedbetween the scanning electrode pair, the electric field which isgenerated between the electrode pair is changed to deflect the ion beamat various angles. As a result, the ion beam performs scanning over ascanning range which is indicated by an arrow X. In FIG. 4, a pluralityof trajectories of the ion beam in the scanning range are indicated bythin solid lines.

The beam scanner 34 causes the ion beam to be incident on the beam dump35 provided at a position away from the beamline BL by deflecting thebeam beyond the scanning range indicated by the arrow X. The beamscanner 34 temporarily retracts the ion beam from the beamline BL towardthe beam dump 35, thereby blocking the ion beam such that the ion beamdoes not reach the substrate transferring/processing unit 20 on thedownstream side.

The beam parallelizer 36 is configured to make a traveling direction ofthe scanning ion beam parallel to the trajectory of the designedbeamline BL. The beam parallelizer 36 has a plurality of arc-shapedparallelizing lens electrodes each of which has an ion beam passage slitprovided at a central portion. The parallelizing lens electrodes areconnected to high-voltage power sources (not shown), and cause electricfields which are generated by application of voltages to act on the ionbeam, thereby making the traveling directions of the ion beam parallelto each other. The beam parallelizer 36 may be replaced with anotherbeam parallelizing device, and the beam parallelizing device may beconfigured as a magnet device using a magnetic field.

The final energy filter 38 is configured to analyze the energy of theion beam and deflect ions having the desired energy downward (to the −ydirection) to lead them to the substrate transferring/processing unit20. The final energy filter 38 is sometimes referred to as an angularenergy filter (AEF) and has an AEF electrode pair for deflection by anelectric field. The AEF electrode pair is connected to a high-voltagepower source (not shown). In FIG. 5C, a positive voltage is applied tothe upper AEF electrode, and a negative voltage is applied to the lowerAEF electrode, whereby the ion beam is deflected downward. The finalenergy filter 38 may be configured with a magnetic device for deflectionby a magnetic field, or may be configured with a combination of the AEFelectrode pair for deflection by the electric field and the magnetdevice.

The left and right Faraday cups 39L and 39R are provided on thedownstream side of the final energy filter 38, and are disposed atpositions where the beams can be incident on the Faraday cups at theleft and right ends of the scanning range indicated by the arrow X. Theleft and right Faraday cups 39L and 39R are provided at positions wherethe Faraday cups do not block the beam which is directed toward thewafer W, and measure a beam current during ion implantation into thewafer W.

The substrate transferring/processing unit 20 is provided on thedownstream side of the beam transport unit 18, that is, farthestdownstream of the beamline BL. The substrate transferring/processingunit 20 includes an implantation process chamber 40, a beam monitor 42,a substrate transfer device 44, and a load port 46. The implantationprocess chamber 40 is provided with a platen driving device (not shown)which holds the wafer W during ion implantation and moves the wafer W ina direction (y direction) perpendicular to the beam scanning direction(x direction).

The beam monitor 42 is provided farthest downstream of the beamline BLin the interior of the implantation process chamber 40. The beam monitor42 is provided at a position where the ion beam can be incident in acase where the wafer W is not present on the beamline BL, and isconfigured to measure the beam current before or during the ionimplantation process. The beam monitor 42 is located, for example, neara transfer port 43 that connects the implantation process chamber 40 andthe substrate transfer device 44, and is provided at a positionvertically below the transfer port 43.

The substrate transfer device 44 is configured to transfer the wafer Wbetween the load port 46 in which a wafer cassette 45 is placed and theimplantation process chamber 40. The load port 46 is configured suchthat a plurality of the wafer cassettes 45 can be placed therein at thesame time, and has, for example, four placing tables arranged in the xdirection. A wafer cassette transfer port 47 is provided verticallyabove the load port 46, and is configured such that the wafer cassette45 can pass in the vertical direction as indicated by an arrow Y. Thewafer cassette 45 is automatically loaded into the load port 46 andautomatically unloaded from the load port 46 through the wafer cassettetransfer port 47 by, for example, a transfer robot which is installed ona ceiling or the like in a semiconductor manufacturing factory where theion implanter 100 is installed.

The ion implanter 100 further includes a central control unit 50. Thecentral control unit 50 controls the overall operation of the ionimplanter 100. The central control unit 50 is realized by elements anddevices such as a CPU and a memory of a computer in terms of hardware,and is realized by a computer program or the like in terms of software.Various functions which are provided by the central control unit 50 canbe realized by cooperation of hardware and software.

An operation panel 49 having a display device and an input device forsetting the operation mode of the ion implanter 100 is provided in thevicinity of the central control unit 50. The positions of the centralcontrol unit 50 and the operation panel 49 are not particularly limited.However, for example, the central control unit 50 and the operationpanel 49 can be disposed to be adjacent to a doorway 48 of themaintenance area MA between the beam generation unit 12 and thesubstrate transferring/processing unit 20. The ion source 10, the loadport 46, the central control unit 50, and the operation panel 49, whichare frequently operated by a worker who manages the ion implanter 100,are provided to be adjacent to each other, whereby work efficiency canbe improved.

The ion implanter 100 has a neutron ray source in which a neutron raycan be generated due to collision of an ion beam having a ultrahighenergy of 4 MeV or more. A member which can serve as the neutron raysource is a member on which an ultrahigh energy ion beam can becontinuously incident in a certain process, and is a slit, a beammonitor, a beam dump, or the like. Specifically, as the slit which canserve as the neutron ray source, the beam profile slit 23, the energyanalyzing slit 27, or the like can be given as an example. Further, asthe beam monitor which can serve as the neutron ray source, the firstFaraday cup 28, the second Faraday cup 31, the left and right Faradaycups 39L and 39R, the beam monitor 42, or the like can be given as anexample. Further, the beam dump 35 provided downstream of the beamscanner 34 can also serve as the neutron ray source. In FIG. 4 and FIGS.5A to 5C, the constituent elements of the beamline which can serve asthe neutron ray sources are painted in black.

The ion implanter 100 includes a plurality of neutron ray measuringinstruments 51, 52, 53, and 54 for monitoring neutron rays which can begenerated in the implanter. The dose rate of the neutron ray which canbe generated in the ion implanter 100 is not so large and can be a valueclose to a detection limit of a general neutron ray measuringinstrument, and thus, the neutron ray measuring instrument is disposedin the vicinity of the neutron ray source in order to improvemeasurement accuracy. The first neutron ray measuring instrument 51 isdisposed in the vicinity of the beam profile slit 23, and the secondneutron ray measuring instrument 52 is disposed in the vicinity of theenergy analyzing slit 27 and the first Faraday cup 28. The third neutronray measuring instrument 53 is disposed in the vicinity of the finalenergy filter 38 which is located between the beam dump 35 and the leftand right Faraday cups 39L and 39R, and the fourth neutron ray measuringinstrument 54 is disposed in the vicinity of the beam monitor 42.

The disposition of the neutron ray measuring instruments is onlyexemplification, and the neutron ray measuring instruments may bedisposed in locations, the number of which is smaller or larger thanthat of the locations shown in the drawing. For example, an additionalor alternative neutron ray measuring instrument may be disposed in thevicinity of the second Faraday cup 31 or the beam dump 35. Further, aplurality of neutron ray measuring instruments may be provided at thesame location, and for example, each of the neutron ray measuringinstruments 51 to 54 which are disposed at the four locations in FIG. 4may have a plurality of (for example, two or three) neutron raymeasuring instruments.

At least apart of the enclosure 60 scatters the neutron rays which aregenerated in the main body 58 such that the neutron dose rate in theexternal space E outside of the enclosure 60 is equal to or less than apredetermined reference value. The enclosure 60 includes a side wallportion 61 which is provided on the side of the main body 58, a ceilingportion 62 which is provided vertically above the main body 58, and afloor portion 63 which is provided vertically below the main body 58, asshown in FIGS. 5A to 5C. The enclosure 60 encloses a substantiallyrectangular parallelepiped internal space F which is occupied by themain body 58.

A neutron ray scattering member is at least partially mounted to each ofthe side wall portion 61, the ceiling portion 62, and the floor portion63. On the other hand, a neutron ray scattering member is not mounted toa part of the enclosure 60 which is disposed along a partial section ofthe beamline, that is, a part of the side wall portion 61, the ceilingportion 62, and the floor portion 63. In the drawing, a neutron rayscattering member is provided in a hatched portion, and a neutron rayscattering member is not provided in a non-hatched portion.

At least a part of each of the side wall portion 61, the ceiling portion62, and the floor portion 63 can be configured, for example, in the samemanner as the accommodation part 71 or the non-accommodation part 72described above. A slide door or a hinged door can be provided at anyposition of the enclosure 60, and a neutron ray scattering member may bemounted to the door structure.

The side wall portion 61 has a first side wall portion 61 a which isdisposed in the vicinity of or around the beam generation unit 12. Thebeam generation unit 12 is a portion through which a low-energy ion beampasses before being accelerated to ultrahigh energy, and does not serveas a neutron ray source. Further, since the first side wall portion 61 ais provided at a position 5 m to 10 m or more away from the neutron raysource, a neutron ray scattering member is not provided therein. Forexample, the first side wall portion 61 a is configured in the samemanner as the non-accommodation part 72 described above.

The side wall portion 61 has a second side wall portion 61 b and a thirdside wall portion 61 c which are disposed along the beam accelerationunit 14. Since the second side wall portion 61 b is disposed along thefirst linear acceleration unit 22 a and the second linear accelerationunit 22 b through which the ion beam passes before being accelerated toultrahigh energy, a neutron ray scattering member is not providedtherein. On the other hand, since the third side wall portion 61 c is aportion which is disposed along the third linear acceleration unit 22 cthrough which the ultrahigh energy ion beam passes, and is disposed inthe vicinity of the beam profile slit 23 which can serve as a neutronray source, a neutron ray scattering member is provided therein. Thesecond side wall portion 61 b is configured, for example, in the samemanner as the non-accommodation part 72 described above. The third sidewall portion 61 c is configured, for example, in the same manner as theaccommodation part 71 described above. The third side wall portion 61 cmay be configured in the same manner as the second accommodation part 71b, and the second neutron ray scattering member 76 b having a smallthickness may be provided therein.

The side wall portion 61 has a fourth side wall portion 61 d, a fifthside wall portion 61 e, and a sixth side wall portion 61 f which aredisposed along the beam deflection unit 16. The beam deflection unit 16has the energy analyzing slit 27, the first Faraday cup 28, and thesecond Faraday cup 31 which can serve as neutron ray sources, and thus,neutron ray scattering members are provided in the side wall portions 61d to 61 f in the vicinity of the beam deflection unit 16.

Since the fourth side wall portion 61 d is disposed in the vicinity ofthe energy analyzing electromagnet 24 in which the beamline BL has anarc shape, the distance from the beamline BL to the fourth side wallportion 61 d is relatively large. For this reason, a neutron rayscattering member having a small thickness is provided in the fourthside wall portion 61 d. Similarly, the sixth side wall portion 61 f isdisposed in the vicinity of the deflection electromagnet 30 in which thebeamline BL has an arc shape, and the distance from the beamline BL tothe sixth side wall portion 61 f is relatively large. Therefore, aneutron ray scattering member having a small thickness is providedtherein. The fourth side wall portion 61 d and the sixth side wallportion 61 f are configured in the same manner as the secondaccommodation part 71 b described above, and the second neutron rayscattering member 76 b having a small thickness may be provided therein.

The fifth side wall portion 61 e is disposed in the vicinity of thelaterally focusing quadrupole lens 26, the energy analyzing slit 27, andthe first Faraday cup 28 in which the beamline BL has a linear shape,and is parallel to the beamline BL. The fifth side wall portion 61 e isdisposed close to the beamline BL from the viewpoint of reducing theoccupied area of the enclosure 60. The distance from the energyanalyzing slit 27 or the first Faraday cup 28 which serves as a neutronray source to the fifth side wall portion 61 e is small and is, forexample, 2 m or less, 1.5 m or less, or 1 m or less. Further, since theneutron ray which is directed from the energy analyzing slit 27 or thefirst Faraday cup 28 toward the fifth side wall portion 61 e travelsapproximately in the thickness direction of the fifth side wall portion61 e, it is also difficult to increase the effective thickness throughwhich the neutron ray passes. For this reason, a neutron ray scatteringmember having a large thickness is provided in the fifth side wallportion 61 e, and the thickness thereof is, for example, 150 mm or more,200 mm or more, or 300 mm or more. The fifth side wall portion 61 e maybe configured in the same manner as the first accommodation part 71 adescribed above, and the first neutron ray scattering member 76 a havinga large thickness may be provided therein.

The side wall portion 61 has a seventh side wall portion 61 g which isdisposed along the beam transport unit 18. The seventh side wall portion61 g is disposed in the vicinity of the beam shaper 32, the beam scanner34, and the beam parallelizer 36 which are located on the upstream sideof the beam transport unit 18. Although the second Faraday cup 31 or thebeam dump 35 which can serve as a neutron ray sources is present in thevicinity of the seventh side wall portion 61 g, the distances from theseneutron ray sources to the seventh side wall portion 61 g are relativelylarge. For this reason, a neutron ray scattering member having a smallthickness is provided in the seventh side wall portion 61 g. The seventhside wall portion 61 g may be configured in the same manner as thesecond accommodation part 71 b described above, and the second neutronray scattering member 76 b having a small thickness may be providedtherein.

The side wall portion 61 has an eighth side wall portion 61 h which isdisposed along the final energy filter 38, the implantation processchamber 40, and the substrate transfer device 44. The eighth side wallportion 61 h is disposed in the vicinity of the beam monitor 42 on whichthe ultrahigh energy ion beam can be incident frequently, and theneutron dose rate attributable to the beam monitor 42 is relativelyhigh. Therefore, a neutron ray scattering member having a largethickness is provided therein. The eighth side wall portion 61 h may beconfigured in the same manner as the first accommodation part 71 adescribed above, and the first neutron ray scattering member 76 a havinga large thickness may be provided therein.

The side wall portion 61 has a ninth side wall portion 61 i which isdisposed so as to surround the load port 46. The ninth side wall portion61 i has a portion which is disposed in front of the load port 46 andother portions which are disposed on the sides of the load port 46. Adoorway to the load port 46 and front doors are provided in the ninthside wall portion 61 i. Since the ninth side wall portion 61 i isdisposed in the vicinity of the beam monitor 42, a neutron rayscattering member is provided therein. Since the distance from the beammonitor 42 toward the ninth side wall portion 61 i is short, it ispreferable that a neutron ray scattering member having a large thicknessis provided in the ninth side wall portion 61 i. However, if thethicknesses of the front doors are too large, it takes effort to openand close the front door, leading to a degradation in convenience.Therefore, by disposing additional neutron ray scattering members 64 aand 64 b between the beam monitor 42 and the load port 46, the thicknessof the neutron ray scattering member required for the ninth side wallportion 61 i is reduced. The ninth side wall portion 61 i may beconfigured in the same manner as the second accommodation part 71 bdescribed above, and the second neutron ray scattering member 76 bhaving a small thickness may be provided therein.

Also with respect to the ceiling portion 62 and the floor portion 63,neutron ray scattering members are provided in the same way as the sidewall portion 61. That is, a neutron ray scattering member is disposedmainly in the vicinity of the neutron ray source or at a location wherethe distance from the neutron ray source to the ceiling portion 62 orthe floor portion 63 is short, and at the other locations, the neutronray scattering member is made thin or a neutron ray scattering member isnot provided.

In FIG. 5A, the ceiling portion 62 has a first ceiling portion 62 a inwhich a neutron ray scattering member is not provided, and a secondceiling portion 62 b in which a neutron ray scattering member isprovided. The first ceiling portion 62 a is disposed along the beamgeneration unit 12 and the upstream side of the beam acceleration unit14 (the first linear acceleration unit 22 a and the second linearacceleration unit 22 b). The second ceiling portion 62 b is disposedalong the downstream side of the beam acceleration unit 14 (the thirdlinear acceleration unit 22 c and the beam profile slit 23). Since thesecond ceiling portion 62 b has a short distance from the beam profileslit 23 which can serve as a neutron ray source (for example, within 1m), the thickness of the neutron ray scattering member is changedstepwise according to the distance from the beam profile slit 23. Forexample, in the second ceiling portion 62 b, the shorter the distancefrom the beam profile slit 23 becomes, the further the number of stackedplate-shaped neutron ray scattering members is increased.

In FIG. 5A, the floor portion 63 has a first floor portion 63 a in whicha neutron ray scattering member is not provided, and a second floorportion 63 b in which a neutron ray scattering member is provided. Thefirst floor portion 63 a is disposed along the beam generation unit 12and the upstream side of the beam acceleration unit 14. The second floorportion 63 b is disposed in the vicinity of the beam profile slit 23.From the viewpoint of securing a foothold at the time of mounting ormaintenance work of the main body 58, it is preferable that the floorportion 63 is configured to be as flat as possible. In other words, itis not preferable that the upper surface of the floor portion 63 isconfigured in a step shape due to partially disposing a thick neutronray scattering member on the floor portion 63. Therefore, additionalneutron ray scattering members 64 c and 64 d are disposed on the lowersurface of the third linear acceleration unit 22 c or a chamberaccommodating the beam profile slit 23, and thus the thickness of theneutron ray scattering member required for the second floor portion 63 bis reduced.

In FIG. 5B, the ceiling portion 62 has a third ceiling portion 62 c inwhich a neutron ray scattering member is provided. The third ceilingportion 62 c is disposed along the beam deflection unit 16. The thirdceiling portion 62 c is configured such that in the vicinity of theenergy analyzing slit 27 or the first Faraday cup 28 which can serve asa neutron ray source, the shorter the distance from the neutron raysource becomes, the larger the thickness of the neutron ray scatteringmember becomes, in the same way as the second ceiling portion 62 b.

In FIG. 5B, the floor portion 63 has a third floor portion 63 c in whicha neutron ray scattering member is provided. The third floor portion 63c is disposed along the beam deflection unit 16. Further, an additionalneutron ray scattering member 64 e is disposed on the lower surface ofthe device configuring the beam deflection unit 16. The additionalneutron ray scattering member 64 e is disposed in the vicinity of theenergy analyzing slit 27 or the first Faraday cup 28 which can serve asa neutron ray source, and is configured such that the shorter thedistance from the neutron ray source becomes, the larger the thicknessof the neutron ray scattering member becomes. By disposing theadditional neutron ray scattering member 64 e, the thickness of theneutron ray scattering member required for the third floor portion 63 cis reduced.

In FIG. 5C, the ceiling portion 62 has a fourth ceiling portion 62 d anda fifth ceiling portion 62 e in which neutron ray scattering members areprovided. The fourth ceiling portion 62 d is disposed along the beamtransport unit 18, and the fifth ceiling portion 62 e is disposed alongthe substrate transferring/processing unit 20. The fourth ceilingportion 62 d is configured such that the thickness of the neutron rayscattering member increases in the vicinity of each of the secondFaraday cup 31 and the beam dump 35 which can serve as neutron raysources. Further, an additional neutron ray scattering member 64 g isprovided in the vicinity of the beam dump 35 above the beam scanner 34.The fifth ceiling portion 62 e is configured such that the shorter thedistance from the beam monitor 42 which can serve as a neutron raysource becomes, the larger the thickness of the neutron ray scatteringmember becomes.

In FIG. 5C, the floor portion 63 has a fourth floor portion 63 d and afifth floor portion 63 e in which neutron ray scattering members areprovided. The fourth floor portion 63 d is disposed along the beamtransport unit 18, and the fifth floor portion 63 e is disposed alongthe substrate transferring/processing unit 20. The fourth floor portion63 d is configured such that the thickness of the neutron ray scatteringmember is uniform. An additional neutron ray scattering member 64 f isdisposed on the lower surface of the main body 58 in the vicinity of thesecond Faraday cup 31. By disposing the additional neutron rayscattering member 64 f, the thickness of the neutron ray scatteringmember required for the fourth floor portion 63 d is reduced. The fifthfloor portion 63 e is configured such that the thickness of the neutronray scattering member is increased in the vicinity of the implantationprocess chamber 40 in which the beam monitor 42 is provided. A neutronray scattering member is not provided in a floor portion (a sixth floorportion) 63 f for the substrate transfer device 44 and the load port 46.This is because the neutron dose rate of the neutron ray which isdirected from the beam monitor 42 toward the sixth floor portion 63 fcan be sufficiently reduced due to the additional neutron ray scatteringmember 64 a which is disposed between the implantation process chamber40 and the substrate transfer device 44.

In FIG. 5C, the additional neutron ray scattering members 64 a and 64 bwhich are provided in the substrate transferring/processing unit 20 aredisposed so as not to interfere with the transfer of the wafer W betweenthe implantation process chamber 40 and the load port 46. Specifically,a configuration is made such that a neutron ray scattering member is notdisposed on a horizontal wafer transfer path indicated by an arrow Z atthe height position where the transfer port 43 is provided. That is, theadditional neutron ray scattering members 64 a and 64 b are disposed soas not to overlap each other in the horizontal direction. On the otherhand, in order to prevent the neutron ray from leaking to the outsidethrough the horizontal wafer transfer path indicated by the arrow Z, theninth side wall portion 61 i which includes a neutron ray scatteringmember is provided in front of the load port 46. The ninth side wallportion 61 i is disposed so as to partially overlap each of theadditional neutron ray scattering members 64 a and 64 b in thehorizontal direction.

In FIG. 5C, the additional neutron ray scattering member 64 b which isprovided in the substrate transferring/processing unit 20 is disposed soas not to interfere with the transfer of the wafer cassette indicated bythe arrow Y in the vertical direction through the wafer cassettetransfer port 47. That is, the additional neutron ray scattering member64 b is disposed away from the ninth side wall portion 61 i in thehorizontal direction with the wafer cassette transfer port 47 interposedtherebetween. On the other hand, in order to prevent the neutron rayfrom leaking to the outside through the wafer cassette transfer port 47,the additional neutron ray scattering member 64 b and the ninth sidewall portion 61 i are disposed so as to partially overlap each other inthe horizontal direction.

FIG. 6 is a top view schematically showing the structure of a front door80 in front of the load port 46. The load port 46 has four placingtables 46 a to 46 d which are arranged in a line in the left-rightdirection (the direction of an arrow S). A doorway 81 surrounded by apart of the ninth side wall portion 61 i of FIG. 4 is provided in frontof the load port 46, and two slide doors 82 and 83 and one hinged door84 are provided so as to be able to open and close the doorway 81. Aneutron ray scattering member is mounted to each of the doors 82 to 84configuring the front door 80.

The first slide door 82 is configured to be slidable in the left-rightdirection along a first rail 85 extending in the left-right direction,and the second slide door 83 is configured to be slidable in theleft-right direction along a second rail 86 extending in the left-rightdirection. The first slide door 82 and the second slide door 83 aredisposed at different positions in a depth direction, and the firstslide door 82 is disposed on the far side and the second slide door 83is disposed on the near side in the front view of the load port 46. Thehinged door 84 is configured to be rotatable as indicated by an arrow Rwith a hinge 87 provided at the right end of the doorway 81 as a rotaryshaft.

In the closed state of the front door 80 shown in FIG. 6, the firstslide door 82 is disposed at the center of the doorway 81, the secondslide door 83 is disposed on the left side of the doorway 81, and thehinged door 84 is disposed on the right side of the doorway 81. In otherwords, the hinged door 84 closes the right end of the doorway 81, andthe two slide doors 82 and 83 close the remaining region of the doorway81 which is not closed by the hinged door 84. In the closed state, thefirst slide door 82 and the second slide door 83 are configured topartially overlap each other in the depth direction, and the first slidedoor 82 and the hinged door 84 are also configured to partially overlapeach other in the depth direction. The hinged door 84 is configured suchthat the position thereof in the depth direction corresponds to that ofthe second slide door 83 in the closed state.

FIGS. 7A and 7B are top views schematically showing the front door 80 inthe open state. FIG. 7A shows a state where the left side of the doorway81 is opened. The hinged door 84 has been opened toward the near side,and the first slide door 82 and the second slide door 83 have been slidto the right side of the doorway 81. As a result, a state is createdwhere the front sides of both the first placing table 46 a and thesecond placing table 46 b disposed on the left side are opened. FIG. 7Bshows a state where the right side of the doorway 81 is opened. Thehinged door 84 has been opened toward the near side, and the first slidedoor 82 and the second slide door 83 have been slid to the left side ofthe doorway 81. As a result, a state is created where the front sides ofboth the third placing table 46 c and the fourth placing table 46 ddisposed on the right side are opened.

According to this embodiment, in the load port 46 provided with the fourplacing tables 46 a to 46 d, the entire front of the two placing tableson either of the left side or the right side can be opened in the openstate by combining the three doors 82 to 84, and a working space with amargin in the left-right direction can be provided. In a case where thefront door 80 is composed of only two slide doors, since the two slidedoors are disposed so as to overlap each other in the vicinity of thecenter of the doorway 81, the front sides of the two central placingtables 46 b and 46 c cannot be opened widely. Further, in a case wherethe front door 80 is composed of three slide doors, the three slidedoors need to be disposed to be shifted from each other in the depthdirection, and thus the thickness of the entire front door 80 in thedepth direction is increased. In this embodiment, a neutron rayscattering member having a large thickness (for example, about 200 mm)is mounted to each of the doors 82 to 84 configuring the front door 80,and thus, in a case where three slide doors are adopted, the depth ofthe front door 80 is increased. On the other hand, according to thisembodiment, by combining two slide doors and one hinged door, thedoorway 81 can be widely opened while the depth of the front door 80 isreduced.

In the front door 80 shown in FIG. 6 and FIGS. 7A and 7B, aconfiguration is made in which the hinged door 84 is provided on theright side of the doorway 81. However, the hinged door 84 may beprovided on the left side of the doorway 81. That is, the front door 80may be configured so as to be symmetric in the left-right direction withrespect to the illustrated structure. In addition, a configuration maybe made such that a first hinged door is disposed on the left side ofthe doorway 81, a second hinged door is disposed on the right side ofthe doorway 81, and one slide door is disposed at the center of thedoorway 81.

Next, the measurement of the neutron ray will be described. The centralcontrol unit 50 acquires the measurement value in each of the pluralityof neutron ray measuring instruments 51 to 54 shown in FIG. 4 andmonitors the generation status of the neutron rays. The central controlunit 50 estimates the position at least one of the neutron ray sources,based on the measurement values in the plurality of neutron raymeasuring instruments 51 to 54, and estimates the intensity of theneutron ray which is emitted from at least one of the neutron raysources whose position is estimated.

For example, in a case where a neutron ray is detected in the firstneutron ray measuring instrument 51 or the second neutron ray measuringinstrument 52 and a neutron ray is not detected in the third neutron raymeasuring instrument 53 and the fourth neutron ray measuring instrument54, it is estimated that there is a neutron ray source on the upstreamside of the beamline BL. In this case, by analyzing the magnitude of themeasurement value in each of the first neutron ray measuring instrument51 and the second neutron ray measuring instrument 52, it is possible toestimate the neutron ray source in which the neutron ray is beinggenerated. For example, in a case where the measurement value in thefirst neutron ray measuring instrument 51 is large and the measurementvalue in the second neutron ray measuring instrument 52 is small, it isestimated that the beam profile slit 23 is a neutron ray source.Further, in a case where the measurement value in the first neutron raymeasuring instrument 51 is small and the measurement value in the secondneutron ray measuring instrument 52 is large, it is estimated that atleast one of the energy analyzing slit 27, the first Faraday cup 28, andthe second Faraday cup 31 is a neutron ray source. Further, in a casewhere both the measurement value in the first neutron ray measuringinstrument 51 and the measurement value in the second neutron raymeasuring instrument 52 are large, it is estimated that there is apossibility that all of the beam profile slit 23, the energy analyzingslit 27, the first Faraday cup 28, and the second Faraday cup 31 may beneutron ray sources. Conversely, in a case where neutron rays are notdetected in the first neutron ray measuring instrument 51 and the secondneutron ray measuring instrument 52 and a neutron ray is detected in thethird neutron ray measuring instrument 53 or the fourth neutron raymeasuring instrument 54, it is estimated that there is a neutron raysource on the downstream side of the beamline BL. By estimating theposition of the neutron ray source, it is also possible to estimate theintensity of the neutron ray which is emitted from the neutron raysource whose position is estimated, based on the dispositions anddistances of the plurality of neutron ray measuring instruments 51 to 54with respect to the neutron ray source whose position is estimated.

The central control unit 50 may estimate the dose rate distribution ofthe neutron rays in the internal space F inside of the enclosure 60,based on the measurement values in the plurality of neutron raymeasuring instruments 51 to 54. The central control unit 50 may estimatethe neutron dose rate outside of the enclosure 60, based on themeasurement values in the plurality of neutron ray measuring instruments51 to 54. The central control unit 50 may estimate, for example, theposition and the neutron dose rate of the neutron ray source, andcalculate the neutron dose rate at any position in the external space Eor the internal space F of the enclosure 60 by simulation or the like,based on the estimated position and the estimated neutron dose rate ofthe neutron ray source. The neutron dose rate inside or outside of theenclosure 60 may be calculated in consideration of the disposition ofthe main body 58, the disposition of the enclosure 60, the dispositionof the neutron ray scattering member which is provided in the enclosure60, and the disposition of the neutron ray scattering member which isprovided separately from the enclosure 60. In a case where thecalculated neutron dose rate inside or outside of the enclosure 60exceeds a predetermined upper limit value, the central control unit 50may output an alert, temporarily stop the transport of the ion beam, orchange an operation condition of at least one of a plurality of devicesconfiguring the main body 58 such that the neutron dose rate becomesless than the upper limit value.

The central control unit 50 may monitor at least one of the plurality ofdevices which are disposed along the beamline BL, based on themeasurement values in the plurality of neutron ray measuring instruments51 to 54. Specifically, abnormality of at least one of the plurality ofdevices configuring the main body 58 may be detected, or a device thatneeds maintenance may be estimated among the plurality of devices. Thecentral control unit 50 may determine whether at least one device to bemonitored is normal or abnormal, by using information on the operationmode of the main body 58. This is because a location serving as aneutron ray source or a neutron dose rate which is generated in theneutron ray source can be different according to the operation mode ofthe main body 58. Hereinafter, operation modes causing situations whereneutron rays can be generated will be described with reference to FIGS.8 to 14.

FIG. 8 is a flowchart showing a flow of an ion implantation processaccording to an embodiment, and shows a flow of ion implantation intothe wafer W after adjustment of the ion beam. FIGS. 9 to 14schematically show the operation modes of the main body 58, thepositions of the neutron ray sources, and neutron rays 90 to 97 whichare detected by the plurality of neutron ray measuring instruments 51 to54 in each process. In FIGS. 9 to 14, the reaching ranges of the ionbeams passing through the beamline BL are indicated by thick lines, andmain neutron ray sources are painted in black.

First, in a first process (S10) of FIG. 8, the beam energy is adjusted.FIG. 9 schematically shows the ion implanter 100 in the first process.The first process is performed in a state where the beam profile slit 23is inserted into the beamline BL, the slit width of the energy analyzingslit 27 is narrowed, and the first Faraday cup 28 is inserted into thebeamline BL (this state is also referred to as a first operation mode).In the first process, there is a possibility that a ultrahigh energy ionbeam may collide with the beam profile slit 23, the energy analyzingslit 27, and the first Faraday cup 28 to generate neutron rays.Therefore, in the first process, the beam profile slit 23, the energyanalyzing slit 27, and the first Faraday cup 28 can serve as neutron raysources. In the first process, the neutron ray 90 which is generated inthe beam profile slit 23 is detected mainly by the first neutron raymeasuring instrument 51. Further, the neutron ray 91 which is generatedin the energy analyzing slit 27 or the first Faraday cup 28 is detectedmainly by the second neutron ray measuring instrument 52. The neutronray 90 which is generated in the beam profile slit 23 can also bedetected by the second neutron ray measuring instrument 52. Similarly,the neutron ray 91 which is generated in the energy analyzing slit 27 orthe first Faraday cup 28 can also be detected by the first neutron raymeasuring instrument 51.

Subsequently, in a second process (S12) of FIG. 8, the beam current isadjusted by using the first Faraday cup 28. FIG. 10 schematically showsthe ion implanter 100 in the second process. The second process isperformed in a state where the beam profile slit 23 is retracted fromthe beamline BL, the slit width of the energy analyzing slit 27 isincreased to the normal width, and the first Faraday cup 28 is insertedinto the beamline BL (this state is also referred to as a secondoperation mode). The second process is an operation mode similar to thefirst process in FIG. 9. However, the ultrahigh energy ion beam does notcollide with the beam profile slit 23 and the ultrahigh energy ion beamhardly collides with the energy analyzing slit 27. As a result, in thesecond process, the ultrahigh energy ion beam substantially collideswith only the first Faraday cup 28, and thus the first Faraday cup 28can serve as a neutron ray source. The neutron ray 92 which is generatedin the first Faraday cup 28 can be detected by the first neutron raymeasuring instrument 51 or the second neutron ray measuring instrument52. In the second process, more ultrahigh energy ion beams are incidenton the first Faraday cup 28, and thus, the dose rate of the neutron ray92 which can be generated in the first Faraday cup 28 is higher than inthe first process.

Next, in a third process (S14) of FIG. 8, the beam current is adjustedby using the second Faraday cup 31. FIG. 11 schematically shows the ionimplanter 100 in the third process. The third process is performed in astate where the first Faraday cup 28 is retracted from the beamline BLand the second Faraday cup 31 is inserted into the beamline BL (thisstate is also referred to as a third operation mode). In the thirdprocess, since the ion beam collides with the second Faraday cup 31, thesecond Faraday cup 31 can serve as a main neutron ray source. Theneutron ray 93 which is generated in the second Faraday cup 31 isdetected mainly by the first neutron ray measuring instrument 51 and thesecond neutron ray measuring instrument 52. In the third processes, thedose rate of the neutron ray 93 which is detected by the second neutronray measuring instrument 52 disposed in the vicinity of the secondFaraday cup 31 is relatively large, and the dose rate of the neutron ray93 which is detected by the first neutron ray measuring instrument 51disposed away from the second Faraday cup 31 is relatively small.

Next, in a fourth process (S16) of FIG. 8, the beam current is adjustedby using the beam monitor 42. FIG. 12 schematically shows the ionimplanter 100 in the fourth process. The fourth process is performed inan un-scanning state where the second Faraday cup 31 is retracted fromthe beamline BL and reciprocating scanning of the ion beam is notperformed by the beam scanner 34 (this state is also referred to as afourth operation mode). In the fourth process, since the ion beamcollides with the beam monitor 42, the beam monitor 42 can serve as amain neutron ray source. The neutron ray 94 which is generated in thebeam monitor 42 is detected mainly by the third neutron ray measuringinstrument 53 and the fourth neutron ray measuring instrument 54. In thefourth process, the dose rate of the neutron ray 94 which is detected bythe fourth neutron ray measuring instrument 54 disposed in the vicinityof the beam monitor 42 is relatively large, and the dose rate of theneutron ray 94 which is detected by the third neutron ray measuringinstrument 53 disposed away from the beam monitor 42 is relativelysmall.

Next, in a fifth process (S18) of FIG. 8, the ion beam is temporarilyretracted from the beamline BL and the wafer W into which the ion is tobe implanted is loaded into the implantation process chamber 40. FIG. 13schematically shows the ion implanter 100 in the fifth process. In thefifth process, the ion beam is deflected by using the beam scanner 34,so that a state where the ion beam is incident on the beam dump 35 iscreated (this state is also referred to as a fifth operation mode).Therefore, in the fifth process, the beam dump 35 can serve as a mainneutron ray source. The neutron ray 95 which is generated in the beamdump 35 is detected mainly by the first neutron ray measuring instrument51, the second neutron ray measuring instrument 52, and the thirdneutron ray measuring instrument 53. In the fifth process, the dose rateof the neutron ray 95 which is detected by the third neutron raymeasuring instrument 53 disposed in the vicinity of the beam dump 35 isrelatively large, and the dose rate of the neutron ray 95 which isdetected by the first neutron ray measuring instrument 51 or the secondneutron ray measuring instrument 52 disposed away from the beam dump 35is relatively small.

Next, in a sixth process (S20) of FIG. 8, an ion implantation process isperformed by irradiating the wafer W with the ion beam which isreciprocatingly scanned by using the beam scanner 34. FIG. 14schematically shows the ion implanter 100 in the sixth process. In thesixth process, a state is created where the reciprocating scanning ofthe ion beam is performed by using the beam scanner 34, so that the ionbeam is incident on the left and right Faraday cups 39L and 39R.Further, in the sixth process, a state where the wafer W is mechanicallyreciprocated in the vertical direction is set, so that at least a partof the ion beam which is not incident on the wafer W is incident on thebeam monitor 42 (this state is also referred to as a sixth operationmode). Therefore, in the sixth process, the left and right Faraday cups39L and 39R and the beam monitor 42 can serve as main neutron raysources. The neutron rays 96 which are generated in the left and rightFaraday cups 39L and 39R are detected mainly by the third neutron raymeasuring instrument 53, and the neutron ray 97 which is generated inthe beam monitor 42 is detected mainly by the fourth neutron raymeasuring instrument 54. In the sixth process, since a part of the ionbeam which reaches the implantation process chamber 40 is incident onthe beam monitor 42, the neutron dose rate which can be generated in thebeam monitor 42 is lower than that in the fourth process and thus thedose rate of the neutron ray 97 which is detected by the fourth neutronray measuring instrument 54 also becomes low.

The main body 58 can take various operation modes according to the stateof the main body 58, in addition to the operation mode corresponding toeach of the first to sixth processes.

In this manner, if the operation mode of the main body 58 is changed, alocation which can serve as a neutron ray source and a neutron dose ratewhich is generated in the neutron ray source can also change. Therefore,the central control unit 50 performs abnormality detection correspondingto the operation mode of the main body 58. The central control unit 50monitors the apparatus, based on information on the operation mode ofthe main body 58 and the measurement value in at least one neutron raymeasuring instrument in a specific operation mode. For example, thecriterion of the abnormality detection may be changed according to theoperation mode, and at least one of the plurality of devices may bemonitored by using the criterion corresponding to the operation mode.Further, in a case where the measurement value in at least one neutronray measuring instrument exceeds a reference value which is determinedcorresponding to a specific operation mode, the operation condition ofat least one of the plurality of devices may be changed such that themeasurement value becomes equal to or less than the reference value. Forexample, the operation condition may be changed such that the neutrondose rate decreases, or the beam transport may be temporarily stoppedsuch that a neutron ray is not generated.

In the case of the first operation mode in FIG. 9 or the secondoperation mode in FIG. 10, it can be said that a state is normal wherewhile there is a possibility that the neutron rays 90, 91, and 92 may bedetected by the first neutron ray measuring instrument 51 or the secondneutron ray measuring instrument 52, a neutron ray is not detected bythe third neutron ray measuring instrument 53 and the fourth neutron raymeasuring instrument 54. Therefore, in the first operation mode or thesecond operation mode, the upper limit values of the first neutron raymeasuring instrument 51 and the second neutron ray measuring instrument52 are set to be relatively high, and the upper limit values of thethird neutron ray measuring instrument 53 and the fourth neutron raymeasuring instrument 54 are set to be relatively low (for example, closeto a background noise level). In this way, in a case where a neutron rayis detected by the third neutron ray measuring instrument 53 or thefourth neutron ray measuring instrument 54, it can be detected that someabnormality has occurred in the ion implanter 100. The adjustment of thebeam energy or the beam current may be performed, while monitoring aneutron ray which is generated in at least one of the beam accelerationunit 14 and the beam deflection unit 16 by using the first neutron raymeasuring instrument 51 and the second neutron ray measuring instrument52. In this way, in a case where the measurement value in the firstneutron ray measuring instrument 51 or the second neutron ray measuringinstrument 52 exceeds the upper limit value, it can be detected thatsome abnormality has occurred in the adjustment process of the firstoperation mode or the second operation mode.

In the case of the third operation mode in FIG. 11, since the secondFaraday cup 31 can serve as a main neutron ray source, it can be saidthat a state is normal where a neutron ray is not detected by the firstneutron ray measuring instrument 51 and the second neutron ray measuringinstrument 52, or a trace amount of neutron ray can be detected by thefirst neutron ray measuring instrument 51 or the second neutron raymeasuring instrument 52. For example, it can be said that a state isnormal where the neutron dose rate which is detected by the firstneutron ray measuring instrument 51 disposed away from the secondFaraday cup 31 is smaller than the neutron dose rate which is detectedby the second neutron ray measuring instrument 52 disposed in thevicinity of the second Faraday cup 31. Therefore, in the third operationmode, the adjustment of the beam current may be performed whilemonitoring the neutron ray which is generated in the second Faraday cup31 downstream of the energy analyzer by using the first neutron raymeasuring instrument 51 and the second neutron ray measuring instrument52.

In the case of the fourth operation mode in FIG. 12, since the beammonitor 42 can serve as a main neutron ray source, it can be said that astate is normal where while there is a possibility that a neutron raymay be detected by the third neutron ray measuring instrument 53 or thefourth neutron ray measuring instrument 54, a neutron ray is notdetected by the first neutron ray measuring instrument 51 and the secondneutron ray measuring instrument 52. Therefore, in the fourth operationmode, the upper limit values of the first neutron ray measuringinstrument 51 and the second neutron ray measuring instrument 52 may beset to be relatively low (for example, close to a background noiselevel), and the upper limit values of the third neutron ray measuringinstrument 53 and the fourth neutron ray measuring instrument 54 may beset to be relatively high. In the fourth operation mode, the adjustmentof the beam current may be performed while monitoring the neutron raywhich is generated in the beam monitor 42 by using the third neutron raymeasuring instrument 53 and the fourth neutron ray measuring instrument54.

In the case of the fifth operation mode in FIG. 13, since the beam dump35 can serve as a main neutron ray source, it can be said that a stateis normal where a neutron ray is not detected by the first neutron raymeasuring instrument 51, the second neutron ray measuring instrument 52,and the third neutron ray measuring instrument 53, or a trace amount ofneutron ray can be detected by the first neutron ray measuringinstrument 51, the second neutron ray measuring instrument 52, or thethird neutron ray measuring instrument 53. For example, it can be saidthat a state is normal where the neutron dose rate which is detected bythe first neutron ray measuring instrument 51 or the second neutron raymeasuring instrument 52 disposed away from the beam dump 35 is smallerthan the neutron dose rate which is detected by the third neutron raymeasuring instrument 53 disposed in the vicinity of the beam dump 35.Therefore, in the fifth operation mode, whether the ion beam isappropriately retracted may be monitored while measuring the neutron raywhich is generated in the beam dump 35 by using the first neutron raymeasuring instrument 51, the second neutron ray measuring instrument 52,and the third neutron ray measuring instrument 53. In the fifthoperation mode, in a case where a neutron ray is detected by the fourthneutron ray measuring instrument 54, it may be considered that someabnormality has occurred in the beam retraction, and the loading andunloading of the wafer may be stopped.

In the case of the sixth operation mode in FIG. 14, since the left andright Faraday cups 39L and 39R and the beam monitor 42 can serve as mainneutron ray sources, similar to the fourth operation mode, whether theion implantation process is appropriately performed may be monitoredwhile measuring the neutron ray by using the third neutron ray measuringinstrument 53 and the fourth neutron ray measuring instrument 54. Evenif a neutron ray is not generated in the left and right Faraday cups 39Land 39R and the beam monitor 42, in a case where abnormality occurs inthe final energy filter 38 and the ultrahigh energy ion beam collideswith the AEF electrode pair, there is a possibility that the finalenergy filter 38 may serve as a neutron ray source. In a case where aneutron ray is generated in the final energy filter 38 due to theoccurrence of abnormality, it is assumed that the neutron dose ratewhich is detected by the third neutron ray measuring instrument 53increases. Therefore, in a case where only the neutron dose rate whichis measured by the third neutron ray measuring instrument 53 exceeds theupper limit value which is determined for the sixth operation mode, itmay be considered that abnormality has occurred in the final energyfilter 38, and the ion implantation process may be stopped.

The central control unit 50 may accumulate the measurement values in theplurality of neutron ray measuring instruments 51 to 54 and analyze therelationships between the measurement values in the respective measuringinstruments or the transitions of the measurement values with time lapsein the plurality of operation modes described above. For example, thecorrelation data between the operation mode of the main body 58 and themeasurement values in the plurality of neutron ray measuring instruments51 to 54 in a specific operation mode may be accumulated, and the stateof each device configuring the main body 58 may be estimated based onthe accumulated correlation data. As the state of each device, forexample, whether or not the situation requires maintenance at a certainpoint of time may be estimated, or the timing when maintenance isnecessary in the future may be estimated. Since the neutron dose ratewhich can be generated in the neutron ray source can increase as theamount of boron which is accumulated in the neutron ray source increasesaccording to secular use of the implanter, the necessity or timing ofmaintenance can be estimated by analyzing the increasing tendency of theneutron dose rate which is measured by the measuring instrument.

The central control unit 50 may detect abnormality of at least onemeasuring instrument itself, based on the operation mode of the mainbody 58 and the measurement values in the plurality of neutron raymeasuring instruments 51 to 54 in a specific operation mode. In general,in order to detect abnormality of the neutron ray measuring instrumentitself, it is necessary to dispose a plurality of neutron ray measuringinstruments at the same position and measure neutron rays under the samecondition. However, in a case where it is necessary to measure neutronrays at a plurality of locations because there are a plurality ofneutron ray sources as in this embodiment, if a plurality of neutron raymeasuring instruments are disposed at each of a plurality of locations,the cost increases significantly. Therefore, in this embodiment,abnormality of at least one neutron ray measuring instrument itself maybe detected based on the measurement values in the plurality of neutronray measuring instruments 51 to 54 which are disposed at differentlocations.

In each of the operation modes described above, since a location whichcan serve as a main neutron ray source is determined for each operationmode and the distance from the neutron ray source to each of the neutronray measuring instruments 51 to 54 is also fixed, the ratios between therespective measurement values in the neutron ray measuring instruments51 to 54 in a specific operation mode become almost constant. Therefore,in a case where there is a measurement value that deviates from theratios between the respective measurement values in the neutron raymeasuring instruments 51 to 54 which are determined for each operationmode, abnormality of the measuring instrument itself can be detected orthe measuring instrument in which abnormality has occurred can beestimated. Further, the measuring instrument in which abnormality hasoccurred may be estimated by calculating and comparing the ratiosbetween the respective measurement values in the neutron ray measuringinstruments 51 to 54 in a plurality of operation modes.

According to this embodiment, since locations that can serve as neutronray sources are estimated according to operation modes, neutron rays inthe implanter can be appropriately monitored by using the neutron raymeasuring instruments 51 to 54 which are disposed at a plurality ofpositions (for example, four positions), and the number of those issmaller than the assumed number of neutron ray sources (for example,eight positions). That is, the number of neutron ray measuringinstruments can be reduced compared to a case where neutron raymeasuring instruments are disposed to correspond to each of a pluralityof neutron ray sources on a one-to-one basis, and thus an increase incost due to the disposition of a large number of neutron ray measuringinstruments can be prevented.

The present invention has been described above with reference to each ofthe embodiments described above. However, the present invention is notlimited to each of the embodiments described above, and appropriatecombinations or replacements of the configurations of respectiveembodiments are also included in the present invention. Further, it isalso possible to appropriately rearrange the combinations or theprocessing orders in respective embodiments, based on the knowledge ofthose skilled in the art, or to add modifications such as various designchanges to the embodiment, and embodiments to which such rearrangementor modifications are added can also be included in the scope of thepresent invention.

In the embodiments described above, a case where the plate-shaped orblock-shaped neutron ray scattering member is mounted to the main body58 or the enclosure 60 has been described. In a modification example,grain-type, gel-type, or paste-type neutron ray scattering member may beprovided. For example, the gel-type or paste-type neutron ray scatteringmember may be applied to the surface of the main body 58 or theenclosure 60 or filled in a gap in the main body 58 or the enclosure 60.In addition, the grain-type neutron ray scattering member may be filledin a hollow portion in the support structure of the main body 58 or theenclosure 60.

An aspect of this embodiment is as follows.

(Item 1-1)

An ion implanter including:

a main body which includes a plurality of units which are disposed alonga beamline along which an ion beam is transported, and a substratetransferring/processing unit which is disposed farthest downstream ofthe beamline, and has a neutron ray source in which a neutron ray can begenerated due to collision of a ultrahigh energy ion beam;

an enclosure which at least partially encloses the main body; and

a neutron ray scattering member which is disposed at a position wherethe neutron ray which is emitted from the neutron ray source can beincident in a direction in which a distance from the neutron ray sourceto the enclosure is equal to or less than a predetermined value.

(Item 1-2)

The ion implanter according to the item 1-1, in which the neutron rayscattering member includes a first neutron ray scattering member whichis disposed at a position where the neutron ray which is emitted fromthe neutron ray source can be incident in a first direction in which adistance from the neutron ray source to the enclosure is a firstdistance, and a second neutron ray scattering member which is disposedat a position where the neutron ray which is emitted from the neutronray source can be incident in a second direction in which a distancefrom the neutron ray source to the enclosure is a second distance largerthan the first distance, and has a smaller thickness than the firstneutron ray scattering member.

(Item 1-3)

The ion implanter according to the item 1-1 or 1-2, in which the neutronray scattering member is disposed at a position where the neutron raywhich is emitted from the neutron ray source can be incident in a firstdirection in which a distance from the neutron ray source to theenclosure is a first distance, and is not disposed at a position wherethe neutron ray which is emitted from the neutron ray source can beincident in a third direction in which a distance from the neutron raysource to the enclosure is a third distance larger than the firstdistance.

(Item 1-4)

The ion implanter according to any one of the item 1-1 to the item 1-3,in which the neutron ray source is at least one of a slit, a beammonitor, and a beam dump which are provided in the beamline.

(Item 1-5)

The ion implanter according to any one of the item 1-1 to the item 1-4,in which at least apart of the neutron ray scattering member is mountedto the enclosure.

(Item 1-6)

The ion implanter according to the item 1-5, in which at least a part ofthe neutron ray scattering member is mounted to a door which is providedin the enclosure.

(Item 1-7)

The ion implanter according to any one of the item 1-1 to the item 1-6,in which at least apart of the neutron ray scattering member is mountedto at least one of the main body and a support structure for the mainbody.

(Item 1-8)

The ion implanter according to any one of the item 1-1 to the item 1-7,in which the neutron ray scattering member is not mounted to a part ofthe enclosure which is disposed along a partial section of the beamline.

(Item 1-9)

The ion implanter according to the item 1-8, in which the plurality ofunits include a beam acceleration unit that accelerates an ion beamwhich is extracted from an ion source to generate the ultrahigh energyion beam, and a beam transport unit that transports the ultrahigh energyion beam toward the substrate transferring/processing unit, and

the neutron ray scattering member is at least partially mounted to apart of the enclosure which is disposed along the beam transport unit,and is at least partially not mounted to a part of the enclosure whichis disposed along the beam acceleration unit.

(Item 1-10)

The ion implanter according to the item 1-9, in which the plurality ofunits further include a beam deflection unit that connects the beamacceleration unit and the beam transport unit,

the beamline is formed in a U shape by the beam acceleration unit havinga linear shape, the beam deflection unit having a curved shape, and thebeam transport unit having a linear shape, and

the neutron ray scattering member is at least partially mounted to apart of the enclosure which is disposed along the beam deflection unit.

(Item 1-11)

The ion implanter according to any one of the item 1-1 to the item 1-10,in which the substrate transferring/processing unit includes animplantation process chamber in which an implantation process forirradiating a wafer with the ultrahigh energy ion beam is performed, aload port on which a wafer cassette accommodating a plurality of wafersis placed, and a substrate transfer device which transfers the waferbetween the implantation process chamber and the wafer cassette,

the enclosure has a wafer cassette transfer port configured to allow thewafer cassette to pass in a vertical direction vertically above the loadport, and

the neutron ray scattering member is disposed so as not to interferewith transfer of the wafer cassette in the wafer cassette transfer port.

(Item 1-12)

The ion implanter according to the item 1-11, in which parts of theneutron ray scattering members are disposed so as to overlap in ahorizontal direction with the wafer cassette transfer port interposedtherebetween.

(Item 1-13)

The ion implanter according to the item 1-11 or 1-12, in which theenclosure has a doorway which is provided in front of the load port, onehinged door which closes a right end or a left end of the doorway, andtwo slide doors which close a remaining region of the doorway which isnot closed by the hinged door, and

the neutron ray scattering member is mounted to both the hinged door andthe slide doors.

(Item 1-14)

The ion implanter according to the item 1-11 or 1-12, in which theenclosure has a doorway which is provided in front of the load port, twohinged doors which close a right end and a left end of the doorway, andone slide door which closes a center region of the doorway which is notclosed by the two hinged doors, and

the neutron ray scattering member is mounted to both the hinged doorsand the slide door.

(Item 1-15)

The ion implanter according to any one of the item 1-1 to the item 1-14,in which the enclosure includes a side wall portion which is provided ona horizontal side of the main body, a ceiling portion which is providedvertically above the main body, and a floor portion which is providedvertically below the main body, and

each of the side wall portion, the ceiling portion, and the floorportion has a section to which the neutron ray scattering member ismounted, and a section to which the neutron ray scattering member is notmounted.

(Item 1-16)

The ion implanter according to any one of the item 1-1 to the item 1-15,in which the neutron ray scattering member is made of a material havinga hydrogen atom content in a range from 0.08 g/cm³ to 0.15 g/cm³.

(Item 1-17)

The ion implanter according to any one of the item 1-1 to the item 1-16,in which the neutron ray scattering member includes polyolefin.

(Item 1-18)

The ion implanter according to the item 1-17, in which the neutron rayscattering member further includes a predetermined amount of boronatoms.

(Item 1-19)

The ion implanter according to any one of the item 1-1 to the item 1-18,in which at least a part of the neutron ray scattering member isplate-shaped or block-shaped.

(Item 1-20)

The ion implanter according to the item 1-19, in which an incombustiblesheet is attached to a surface of the plate-shaped or block-shapedneutron ray scattering member.

(Item 1-21)

The ion implanter according to any one of the item 1-1 to the item 1-20,in which at least a part of the neutron ray scattering member isgrain-type, gel-type, or paste-type.

(Item 1-22)

The ion implanter according to any one of the item 1-1 to the item 1-21,further including an X-ray shielding member which is mounted to theenclosure.

(Item 1-23)

The ion implanter according to any one of the item 1-1 to the item 1-22,in which the ultrahigh energy ion beam includes boron ions which have anenergy of 4 MeV or higher.

Another aspect of this embodiment is as follows.

(Item 2-1)

An ion implanter including:

a plurality of devices which are disposed along a beamline along whichan ion beam is transported;

a plurality of neutron ray measuring instruments which are disposed at aplurality of positions in the vicinity of the beamline and measureneutron rays which can be generated at a plurality of locations of thebeamline due to collision of a ultrahigh energy ion beam; and

a control device which monitors at least one of the plurality ofdevices, based on a measurement value in at least one of the pluralityof neutron ray measuring instruments.

(Item 2-2)

The ion implanter according to the item 2-1, in which the control deviceestimates a position of at least one of neutron ray sources in thebeamline, based on measurement values in the plurality of neutron raymeasuring instruments.

(Item 2-3)

The ion implanter according to the item 2-1 or 2-2, in which the controldevice estimates intensity of a neutron ray which is emitted from atleast one of neutron ray sources in the beamline, based on measurementvalues in the plurality of neutron ray measuring instruments.

(Item 2-4)

The ion implanter according to any one of the item 2-1 to the item 2-3,in which at least one of the plurality of neutron ray measuringinstruments is disposed in the vicinity of at least one of a slit, abeam monitor, and a beam dump which are provided in the beamline.

(Item 2-5)

The ion implanter according to any one of the item 2-1 to the item 2-4,in which the control device detects abnormality of at least one of theplurality of devices, based on information on operation modes of theplurality of devices and a measurement value in at least one neutron raymeasuring instrument in a specific operation mode.

(Item 2-6)

The ion implanter according to the item 2-5, in which in a case wherethe measurement value in the at least one neutron ray measuringinstrument exceeds a reference value which is determined correspondingto the specific operation mode, the control device changes an operationcondition of at least one of the plurality of devices such that themeasurement value is equal to or less than the reference value.

(Item 2-7)

The ion implanter according to any one of the item 2-1 to the item 2-6,in which the control device accumulates correlation data betweenoperation modes of the plurality of devices and measurement values inthe plurality of neutron ray measuring instruments in a specificoperation mode, and estimates a device that needs maintenance among theplurality of devices, based on the accumulated correlation data.

(Item 2-8)

The ion implanter according to the item 2-7, in which the control deviceestimates a maintenance timing of at least one of the plurality ofdevices, based on the accumulated correlation data.

(Item 2-9)

The ion implanter according to any one of the item 2-1 to the item 2-8,in which the control device detects abnormality of at least one of theplurality of devices, based on information on operation modes of theplurality of devices and measurement values in at least two or moreneutron ray measuring instruments in a specific operation mode.

(Item 2-10)

The ion implanter according to any one of the item 2-1 to the item 2-9,in which the plurality of devices include a beam acceleration unit thatgenerates the ultrahigh energy ion beam by accelerating an ion beamwhich is extracted from an ion source, and an energy analyzer which isdisposed downstream of the beam acceleration unit, and

the control device adjusts at least one of an energy and a beam currentof an ion beam which exits from the energy analyzer, while monitoringneutron rays which can be generated in at least one of the beamacceleration unit and the energy analyzer, by using at least two or moreneutron ray measuring instruments.

(Item 2-11)

The ion implanter according to the item 2-10, in which the plurality ofneutron ray measuring instruments include a first neutron ray measuringinstrument which is disposed in the vicinity of a slit which is providedat an exit of the beam acceleration unit, and a second neutron raymeasuring instrument which is disposed in the vicinity of a slit and abeam monitor which are provided at an exit of the energy analyzer, and

the control device monitors neutron rays which can be generated in atleast one of the beam acceleration unit and the energy analyzer, byusing the first neutron ray measuring instrument and the second neutronray measuring instrument.

(Item 2-12)

The ion implanter according to the item 2-11, in which the controldevice monitors neutron rays which can be generated downstream of theenergy analyzer in the beamline, by using the first neutron raymeasuring instrument and the second neutron ray measuring instrument.

(Item 2-13)

The ion implanter according to any one of the item 2-1 to the item 2-12,in which the plurality of devices include a beam deflector which appliesat least one of an electric field and a magnetic field to the ion beamand retracts the ion beam toward a beam dump which is provided away fromthe beamline, and

the control device monitors neutron rays which can be generated in thebeam dump when the ion beam is retracted by the beam deflector, by usingat least two or more neutron ray measuring instruments.

(Item 2-14)

The ion implanter according to any one of the item 2-1 to the item 2-13,in which the plurality of neutron ray measuring instruments include athird neutron ray measuring instrument which is disposed upstream of abeam monitor which is provided in the vicinity of an implantationposition where a wafer which is irradiated with the ion beam isdisposed, and a fourth neutron ray measuring instrument which isdisposed downstream of the beam monitor which is provided in thevicinity of the implantation position, and

the control device monitors neutron rays which can be generated in thebeam monitor which is provided in the vicinity of the implantationposition, by using the third neutron ray measuring instrument and thefourth neutron ray measuring instrument.

(Item 2-15)

The ion implanter according to any one of the item 2-1 to the item 2-14,in which the control device detects abnormality of at least one neutronray measuring instrument itself, based on information on operation modesof the plurality of devices and measurement values in the plurality ofneutron ray measuring instruments in a specific operation mode.

(Item 2-16)

The ion implanter according to any one of the item 2-1 to the item 2-15,further including:

an enclosure which encloses the plurality of devices and the pluralityof neutron ray measuring instruments,

in which the control device estimates a neutron dose rate outside of theenclosure, based on measurement values in the plurality of neutron raymeasuring instruments.

(Item 2-17)

The ion implanter according to the item 2-16, in which the controldevice estimates the neutron dose rate outside of the enclosure, basedon disposition of at least one of a neutron ray scattering materialwhich is included in the enclosure and a neutron ray scattering materialwhich is disposed in the vicinity of the beamline.

(Item 2-18)

The ion implanter according to the item 2-16 or 2-17, in which in a casewhere the estimated neutron dose rate outside of the enclosure exceeds apredetermined upper limit value, the control device changes an operationcondition of at least one of the plurality of devices such that theneutron dose rate outside of the enclosure is lowered.

(Item 2-19)

The ion implanter according to any one of the item 2-16 to the item2-18, in which the control device estimates a dose rate distribution ofneutron rays inside of the enclosure, based on measurement values in theplurality of neutron ray measuring instruments.

(Item 2-20)

The ion implanter according to any one of the item 2-1 to the item 2-19,in which the ultrahigh energy ion beam includes boron (B) ions whichhave an energy of 4 MeV or higher.

(Item 2-21)

An ion implantation method including:

measuring neutron rays which can be generated at a plurality oflocations of a beamline due to collision of a ultrahigh energy ion beam,by using a plurality of neutron ray measuring instruments which aredisposed at a plurality of positions in the vicinity of the beamlinealong which an ion beam is transported; and

monitoring at least one of a plurality of devices which are disposedalong the beamline, based on a measurement value in at least one of theplurality of neutron ray measuring instruments.

It should be understood that the invention is not limited to theabove-described embodiment, but may be modified into various forms onthe basis of the spirit of the invention. Additionally, themodifications are included in the scope of the invention.

What is claimed is:
 1. An ion implanter comprising: a main body whichincludes a plurality of units which are disposed along a beamline alongwhich an ion beam is transported, and a substratetransferring/processing unit which is disposed farthest downstream ofthe beamline, and has a neutron ray source in which a neutron ray isgenerated due to collision of a ultrahigh energy ion beam; an enclosurewhich at least partially encloses the main body; and a neutron rayscattering member which is disposed at a position where the neutron raywhich is emitted from the neutron ray source is incident in a directionin which a distance from the neutron ray source to the enclosure isequal to or less than a predetermined value.
 2. The ion implanteraccording to claim 1, wherein the neutron ray scattering member includesa first neutron ray scattering member which is disposed at a positionwhere the neutron ray which is emitted from the neutron ray source isincident in a first direction in which a distance from the neutron raysource to the enclosure is a first distance, and a second neutron rayscattering member which is disposed at a position where the neutron raywhich is emitted from the neutron ray source is incident in a seconddirection in which a distance from the neutron ray source to theenclosure is a second distance larger than the first distance, and has asmaller thickness than the first neutron ray scattering member.
 3. Theion implanter according to claim 1, wherein the neutron ray scatteringmember is disposed at a position where the neutron ray which is emittedfrom the neutron ray source is incident in a first direction in which adistance from the neutron ray source to the enclosure is a firstdistance, and is not disposed at a position where the neutron ray whichis emitted from the neutron ray source is incident in a third directionin which a distance from the neutron ray source to the enclosure is athird distance larger than the first distance.
 4. The ion implanteraccording to claim 1, wherein the neutron ray source is at least one ofa slit, a beam monitor, and a beam dump which are provided in thebeamline.
 5. The ion implanter according to claim 1, wherein at least apart of the neutron ray scattering member is mounted to the enclosure.6. The ion implanter according to claim 5, wherein at least a part ofthe neutron ray scattering member is mounted to a door which is providedin the enclosure.
 7. The ion implanter according to claim 1, wherein atleast a part of the neutron ray scattering member is mounted to at leastone of the main body and a support structure for the main body.
 8. Theion implanter according to claim 1, wherein the neutron ray scatteringmember is not mounted to a part of the enclosure which is disposed alonga partial section of the beamline.
 9. The ion implanter according toclaim 8, wherein the plurality of units include a beam acceleration unitthat accelerates an ion beam which is extracted from an ion source togenerate the ultrahigh energy ion beam, and a beam transport unit thattransports the ultrahigh energy ion beam toward the substratetransferring/processing unit, and the neutron ray scattering member isat least partially mounted to a part of the enclosure which is disposedalong the beam transport unit, and is at least partially not mounted toa part of the enclosure which is disposed along the beam accelerationunit.
 10. The ion implanter according to claim 9, wherein the pluralityof units further include a beam deflection unit that connects the beamacceleration unit and the beam transport unit, the beamline is formed ina U shape by the beam acceleration unit having a linear shape, the beamdeflection unit having a curved shape, and the beam transport unithaving a linear shape, and the neutron ray scattering member is at leastpartially mounted to a part of the enclosure which is disposed along thebeam deflection unit.
 11. The ion implanter according to claim 1,wherein the substrate transferring/processing unit includes animplantation process chamber in which an implantation process forirradiating a wafer with the ultrahigh energy ion beam is performed, aload port on which a wafer cassette accommodating a plurality of wafersis placed, and a substrate transfer device which transfers the waferbetween the implantation process chamber and the wafer cassette, theenclosure has a wafer cassette transfer port configured to allow thewafer cassette to pass in a vertical direction vertically above the loadport, and the neutron ray scattering member is disposed so as not tointerfere with transfer of the wafer cassette in the wafer cassettetransfer port.
 12. The ion implanter according to claim 11, whereinparts of the neutron ray scattering members are disposed so as tooverlap each other in a horizontal direction with the wafer cassettetransfer port interposed therebetween.
 13. The ion implanter accordingto claim 11, wherein the enclosure has a doorway which is provided infront of the load port, one hinged door which closes a right end or aleft end of the doorway, and two slide doors which close a remainingregion of the doorway which is not closed by the hinged door, and theneutron ray scattering member is mounted to both the hinged door and theslide doors.
 14. The ion implanter according to claim 11, wherein theenclosure has a doorway which is provided in front of the load port, twohinged doors which close a right end and a left end of the doorway, andone slide door which closes a center region of the doorway which is notclosed by the two hinged doors, and the neutron ray scattering member ismounted to both the hinged doors and the slide door.
 15. The ionimplanter according to claim 1, wherein the enclosure includes a sidewall portion which is provided on a horizontal side of the main body, aceiling portion which is provided vertically above the main body, and afloor portion which is provided vertically below the main body, and eachof the side wall portion, the ceiling portion, and the floor portion hasa section to which the neutron ray scattering member is mounted, and asection to which the neutron ray scattering member is not mounted. 16.The ion implanter according to claim 1, wherein the neutron rayscattering member is made of a material having a hydrogen atom contentin a range from 0.08 g/cm³ to 0.15 g/cm³.
 17. The ion implanteraccording to claim 1, wherein the neutron ray scattering member includespolyolefin.
 18. The ion implanter according to claim 17, wherein theneutron ray scattering member further includes a predetermined amount ofboron atoms.
 19. The ion implanter according to claim 1, wherein atleast a part of the neutron ray scattering member is plate-shaped orblock-shaped.
 20. The ion implanter according to claim 19, wherein anincombustible sheet is attached on a surface of the plate-shaped orblock-shaped neutron ray scattering member.
 21. The ion implanteraccording to claim 1, wherein at least a part of the neutron rayscattering member is grain-type, gel-type, or paste-type.
 22. The ionimplanter according to claim 1, further comprising: an X-ray shieldingmember which is mounted to the enclosure.
 23. The ion implanteraccording to claim 1, wherein the ultrahigh energy ion beam includesboron ions each of which has an energy of 4 MeV or higher.